1. Field of the Invention
This invention relates in general to cutting devices and in particular to a high speed grinding system and structure for cutting various aggregate and non-aggregate, natural stone and composite building materials having steel or non-steel reinforcing.
2. Background of the Invention
A chain saw is commonly used to fell, buck and delimb trees. The saw chain, the power head, and the coupling components that made up a wood cutting chain saw have been highly developed. The steel cutting links of the saw chain slide along a steel guide bar at a high rate of speed driven by a drive sprocket connected to the drive shaft of the power head. The guide bar is a plate-like member with an oval guide edge provided with a guide slot flanked by guide rails. The saw chain is made up of interconnected center and side link pairs. The center links include a depending tang that slides in the guide grooves and the side links have bottom edges that slide on the guide rails.
The cutting links which are commonly provided as one of the side links of each pair of side links, have an upwardly or outwardly extended portion formed into forwardly directed cutting edges. These cutting edges engage the wood body and cut out wood chips.
The entire process of wood cutting with a chain saw involves metal sliding on metal pounding on metal in reaction to the fast moving chain engaging the wood and removing chips. The wear problem is extremely acute and yet has been largely overcome by metal processing technologies that provide hard metal where wear resistance is desirable, ductile metal where fatigue resistance is desirable, etc. All of this enables the production of a commercially feasible wood cutting tool, i.e., a chain saw with a reasonable life expectancy at a reasonable cost.
Cutting concrete, stone and other hard, brittle materials requires a different type of cutting edge than the one used to cut wood. Typically such materials are cut with small cutting blocks composed of a metal matrix having graded industrial diamond particles impregnated therein. The blocks are attached to a cutting tool, that is, to the periphery of a circular blade, or to a steel cable. Most commonly used are the circular blades.
There are several problems that are encountered by chain saws that do not exist for circular saws. The saw chain and guide system involve numerous parts sliding against each other. The side links and center links pivot relative to each other on rivets or pins, the side link bottom edges slide on the guide bar rails, and center link drive tangs slide in the guide bar groove. Whereas technology developed heretofore enables this sliding relationship for wood cutting, that is not the case for aggregate cutting.
When cutting cement and stone, fine particles are ground out of the aggregate medium creating a dust that settles on the saw chain and its components. This dust gets between the sliding parts of the bar and chain links and acts as an abrasive to rapidly wear the hardest of steel surfaces. Also, the heat that is generated in cutting the hard aggregate materials is so high that similar steel to steel sliding creates an "adhesive" type of wear between engaging parts. This is an inherent welding action that takes place due to the extensive heat that is generated between the parts. Beads of the material are formed in this welding process that break off as particles. Over a period of time, the engaging surfaces are rapidly worn away.
The above problems are however secondary. The primary problem is the provision of a cutting element with sufficient life. Obviously, if the cutting element cannot be retained by the saw chain for any period of time, the fact that the moving or sliding parts are rapidly wearing is of little consequence. The cutting element that is desired for cutting through aggregate material is a metal matrix impregnated with diamonds. It is not practical to make the cutting links entirely of this material. Using a chain saw also limits the working width of the cutting surface since the size of the metal components of the chain determine the narrowest cut possible.
Several prior art patents have attempted to solve the abovementioned problems. U.S. Pat. No. 4,603,678 to Fish discloses a stone cutting device including a continuous flexible cutting belt for cutting a slot in stone which is in the ground. The device includes a main frame, a jib pivotally mounted to the main frame, aligned sheaves rotatably mounted to the main frame and jib, a continuous flexible cutting belt extending around and in driven engagement sheaves, and a means to rotate at least one of the sheaves. The continuous flexible cutting belt includes a plurality of spaced apart abrasive cutting elements extending across the top and sides of the belt. Belt strength is provided by a flexible cable extending through the length of the belt.
U.S. Pat. No. 4,679,541 to Fish is a Continuation-In Part of U.S. Pat. No. 4,603,678 to Fish and includes claims drawn to an embodiment including a groove on the top and bottom edges of the jib and outlet means opening in the groove allowing water to be emitted between the groove and the belt to provide lubrication and reduced vibration as the belt passes through the groove. During operation, the water thus emitted from the jib passes outside the groove and into the cut slot in the stone and washes away stone cuttings for improved operation.
U.S. Pat. No. 4,920,947 to Scott et al discloses a chain saw for cutting aggregate materials including a saw chain of interconnected center links and side link pairs composed of heat-treated steel. Certain pairs of the side links support diamond impregnated matrix cutting blocks that are laser welded to the side links in a process where the laser beam is focused and orbited along the juncture to avoid stress risers in the steel material of the supporting side links. The guide bar is provided with a pattern of enclosed channels for directing water to the guide bar groove at spaced positions on the periphery of the guide bar edge for flushing away the aggregate dust generated by the cutting process.
U.S. Pat. No. 4,971,022 to Scott et al is related to U.S. Pat. No. 4,920,947 above and includes details of a cutting chain for aggregate materials. The cutting link structure is a folded plate-like member formed into spaced side plate portions and an overhead connecting web. The side plate portions function like side links in a conventional saw chain and ride on the rails of a guide bar.
U.S. Pat. No. 5,184,598 to Bell discloses an articulated saw chain for cutting aggregate material. The saw chain has cutting blocks affixed to pairs of side links and guards formed or attached to side link pairs positioned between successive cutting blocks. The guard portions extend to substantially the same height as the cutting block to protect the edge of the cutting blocks from impacting against an object.
U.S. Pat. No. 5,215,072 to Scott discloses a cutting element and saw chain for cutting aggregate material comprising a saw chain having a right and left support links carrying the diamond mesh upon inclined support surfaces relative to the travel axis of the saw chain. The abrasive particle impregnated mesh contacts the material to be cut only adjacent its trailing edge. A consumable material exists between the impregnated mesh and the support surface. The impregnated mesh may extend downward along the side of the support link to maintain a constant kerf width.